In one aspect, this invention relates to a process for hydrovisbreaking liquid hydrocarbon-containing feed streams so as to produce lower boiling hydrocarbons. In another aspect, this invention relates to a multi-stage process for hydrofining liquid hydrocarbon-containing feed streams, in particular metal-containing heavy oil streams. In a further aspect, this invention relates to a multi-stage hydrofining process employing decomposable transition metal compounds as hydrofining agents.
It is well known to hydrotreat (hydrofine) liquid hydrocarbon-containing feed streams such as heavy oils, which contain undesirable metal and sulfur compounds as impurities and also considerable amounts of cokable materials (referred to as Ramsbottom carbon residue), so as to obtain lower boiling materials having lower molecular weight than the feed hydrocarbons and to remove at least a portion of metal and sulfur impurities and cokable materials from the feed. A specific type of hydrotreating process is heat-soaking, preferably with agitation, in the presence of hydrogen, hereinafter referred to as hydrovisbreaking.
One of the operational problems of such hydrovisbreaking processes is the formation of undesirably high amounts of coke. Coke formation represents loss in hydrocarbonaceous materials and may also necessitate a costly separation step. Therefore, there is an ever present need to develop new, more efficient oil hydrotreating processes and to utilize effective hydrotreating agents designed to reduce coke formation.